First of all, this is a first time install for a Megasquirt for me, and finished the assembly last weekend. I have the MS1/ver 3.0 which I assembled from scratch. I had updated the firmware to 029y4a and am running MS1-Extra. I plan to run it full standalone with fuel and spark.

I ran TunerStudio and loaded the basemap from DIYautotune (usdm-mazda-miata-9495-18bp-mt-sequential-3.0.3.msq).

Last weekend, I tried starting the car and it failed to start. I pulled the plug and verified there was no spark. I swapped back to the stock ECU and things worked just fine. I also noticed there was no tach signal in Tunerstudio nor my real tach. The LEDs D14, D16 were also solid as I plugged it in w/o even turning the ignition on... Not sure whether thats normal. According to megalogviewer, there's no spark or injector signals. I have attached the log.

When I built it, I verified everything was working with the stim. It passed all the tests with flying colors. One thing I noticed is the tach more or less stopped working when I loaded the base map from DIYAutotune. I noticed I could enable it to work by disabling "generic wheel", but thought that was normal as the stim cant simulate that sort of signal.

I also didn't have the stock MAF connected and was planning on using the Narrow band for now just to keep things simple. But figured the car would at least start, and the disconnected MAF shouldn't affect the idle circuit to affect starting.

I also built the MS with all the usual mods: PWM IAC/TIP120, Relay Mod and followed the DIYAutotune directions for the MSns-E Input mods, as well as the directions to to Trigger spark via the Stock Ignitors, per How to MegaSquirt your Mazda Miata.

One thing I'm not 100% sure about is the harness, so I pieced together things I found on the web. Maybe someone here has one? I can certainly provide a diagram if thats whats needed next.

It sounds like your crankshaft/cam position sensors are either not wired correctly, your setup on your MS isn't configured properly, or something is off in software. I'd stick with the decoder specified in the DIYautotune map. The problem is that the stim was proving that your MS worked if it was fed a proper tach signal. Now you just need to figure out why the tach signal isn't getting to the MS.

If you have the car apart, i'd recommend making sure that you have all of the grounds wired up. Some people get by without them (running only the one the stock ECU uses) but I have seen people have problems if they don't run a couple dedicated grounds to the engine block. At the very least it won't hurt.

Yeah, point noted about the dedicated grounds and ground to the engine block for less voltage drop and generally better accuracy as I have read. Right now I am grounding just to the harness connector, but figure that should at least provide spark. (see diagram). I'd figure the basemap would also have good decoder settings.

Is it normal to lose tach when you turn the decoder signal to "generic wheel" when using the stim?

Let me know if you guys see something wrong about this diagram. I'll post pictures of the mods later.

Scrap that previous diagram, believe I found some issues with the cas signals. Updated it here, as well as swapping the ignitor wires. Also created ground wires to body just near ecu instead of just relying on harness grounds. Same situation though... no spark :(

Here's my mods. Please note, that I had to relocate Q13 to the prototype area as I jacked up the solder pads. I believe its
part of the PWM flyback circuit, which should not affect spark.

Yes you should be able to get spark running without those items. That said, fix them ASAP. You won't be able to run without MAP signal so even if you figure out the crank trigger thing you will be stuck again and it will **** you off that you can't drive it. Same with the AIT and wideband. Just fix it now and put it behind you.

In regards to your crank and cam triggers, have you verified continuity with the lines from the pin on the DB37 to the crank trigger and then the cam trigger? Double, triple check them. Go from the actual DB 37 plug to the actual pins on the sensor.

I farted around with my cam and crank signals for over a year (off and on) and when I fiinally figured it out it turned out to be a combination of grounding issues and misplaced wire on my harness.